Westinghouse Hilltop 20 Lumens Solar Fence Post Cap Lights for 4x4 Wood Posts (Black, 4 Pack) Bright LED light produces a 20 Lumens output for 6 hours before dimming to 5 Lumens for the remainder of the night Automatically turns off and on with the onset of nightfall Mounts to standard 4 x 4 wood posts. Posts actually measure 3.63" x 3.63" Mounts to standard nominal wood posts that measure 3.5" x 3.5" Post caps are made of plastic; each measures 6" x 5.1"